The present invention relates to sealing the end portions of cathode collector bars used in electrolytic cells for production of aluminum. Such cells (also known as pots) typically have an outer metal shell, refractory lining/filler material defining an area for pooling of aluminum metal and electrolyte, and upper anodes exposed to the electrolyte-aluminum pool. Carbon cathode blocks are located at the bottom of the pool area below the anodes. The cathode collector bars typically are encased in the carbon cathode blocks and have opposite ends that project through holes in the shell walls for connection to external conductor buses. Representative constructions are shown in the following publications and the references cited therein:
U.S. Pat. No. 4,619,750 (Cathode Pot for an Aluminum Electrolytic Cell);
U.S. Pat. No. 6,231,745 (Cathode Collector Bar);
U.S. Pat. No. 6,387,237 (Cathode Collector Bar With Spacer for Improved Heat Balance and Method);
U.S. Patent Publication No. 2008/0308415 (Cathodes for Aluminum Electrolysis Cell With Expanded Graphite Lining);
U.S. Pat. No. 7,618,519 (Cathode Element for Use in an Electrolytic Cell Intended for Production of Aluminum);
U.S. Pat. No. 7,776,190 (Cathodes for Aluminum Electrolysis Cell With Expanded Graphite Lining);
U.S. Patent Publication No. 2010/0258434 (Composite Collector Bar).